Apparatus and method for anchoring sutures

ABSTRACT

A substantially conical suture anchor having a bore in which an end of an insertion tool is inserted. The inserted end of the insertion tool is made of shape retaining material. The bore and base of the suture anchor are angled with respect to the central axis of the suture anchor and preferably are parallel to each other. During insertion, the suture anchor, mounted on the insertion tool, is reoriented to fit into the hole, thereby bending the shape memory end of the insertion tool. When the suture anchor is within cancellous bone tissue, the shape memory of the insertion tool urges the suture anchor to its original position (in which the suture anchor cannot fit through the bone hole). The suture anchor is thereby firmly anchored in the human bone.

BACKGROUND OF THE INVENTION

This invention relates to an apparatus and method for anchoring suturesto a live human bone. More particularly, this invention relates to asuture anchor made of a substantially rigid, preferably biocompatiblematerial, and most preferably a material that can be incorporated intothe bone as a bone graft, such as bone, and an insertion tool having aportion made of a stress-induced shape memory material which is insertedinto the anchor and functions to orient the suture anchor, once insertedin the bone, to securely anchor the suture.

Suture anchors for anchoring a suture to bone so that another bodytissue, such as muscle or ligament, may be sutured to the bone are knownin the art. Such suture anchors come in a variety of shapes and designs.A survey of such suture anchors may be found in James E. Carpenter etal., "Pull-Out Strength of Five Suture Anchors", Arthroscopy, 9(1), pp.109-113 (1993).

For example, harpoon-type or screw-type suture anchors are drilled intocortical bone. Examples of such suture anchors are shown, for example,in Cerrier et al. U.S. Pat. No. 5,100,417 and Hayhurst et al. CanadaPatent No. 2,045,903. Such suture anchors are held in place in any of avariety of manners, such as through self-tapping, by a force fit, or byincluding a resilient portion which flexes to frictionally engage thebone material.

Another type of suture anchor includes a rigid member and a resilient,shape memory member. The resilient member is substantially flush withthe rigid member during insertion, and flexes away from the rigid memberonce lodged inside the bone. Such anchors have been described inGatturna et al. U.S. Pat. Nos. 5,046,513 and 5,192,303. The shape memorymaterial may be made in accordance with, for example, Quin U.S. Pat. No.4,505,767 or Harrison U.S. Pat. No. 4,565,589. Because two differentmaterials are used, this type of suture anchor can be costly anddifficult to manufacture. Moreover, the joining of two dissimilar metalsleads to potential flaws and potential breakage at the joint or weldpoint.

A third type of suture anchor is substantially elongated and is insertedwith its longitudinal axis substantially parallel to the bone holethrough which it is inserted. The suture anchor is then reoriented uponreaching cancellous bone tissue by pulling on the suture attached at aselected point along the suture anchor. Examples of such suture anchorsare shown in Hayhurst et al. U.S. Pat. No. 5,041,129 ("Hayhurst") andNoblitt et al. U.S. Pat. No. 5,203,787 ("Noblitt"). The Hayhurst sutureanchor has a substantially cylindrical rigid body with a central boreand a longitudinal slot extending from one end to approximately themiddle of the rigid body. A suture is positioned inside the centralbore, and the anchor is inserted with the slot entering the bone last.Once the anchor is properly positioned, the suture is pulled through theslot towards the base of the slot, thereby reorienting the suture anchorto fix the anchor in the bone. The Noblitt suture anchor has an offsetportion at which a suture is attached. Once the suture anchor is withincancellous tissue, the suture is pulled, thereby reorienting the sutureanchor so that its longitudinal axis is substantially transverse to thebone hole through which it was inserted. One disadvantage associatedwith this type of anchor is that tugging on the suture to reorient theanchor may put undue stress on the suture (particularly at the base ofthe slot in Hayhurst). Moreover, the introduction technique is undulycomplicated, requiring several types of insertion tools (Noblitt mayprovide additional complications because of the nonuniform thickness ofthe suture anchor along the longitudinal axis). Furthermore, Hayhurst'sslot may structurally weaken the remainder of the suture anchor body,and Noblitt's elongated, narrow ends may tend to break off duringreorientation.

A disadvantage common to all of the above-described suture anchors isthat many are typically formed of metal which may not be biocompatible.Additionally such suture anchors are typically visible during X-ray,magnetic resonance imaging (MRI), and computerized tomography (CT)examinations. Accordingly, these suture anchors may interfere withnoninvasive examinations of the treated area. Moreover, theabove-described suture anchors typically require complex insertiontools, the use of which is time consuming. There is thus greaterpotential for later complications such as bone weakening.

Two other anchoring means are staples and cement. The former isgenerally not desirable because staples can crack the bone in which theyare inserted or damage the tissue to be connected to the bone. Thelatter is generally not desirable because of substance compatibility,the need for particular surface characteristics for adequate bonding,and excessive setting times.

It therefore would be desirable to provide an apparatus for anchoring asuture to a bone which is simple to manufacture and to insert, whichdoes not interfere with noninvasive examinations such as radiographs,MRI, or CT, and which is biocompatible and most preferably, capable ofbeing incorporated into the bone as a bone graft, to strengthen thebone. Alternatively, the apparatus may be bioabsorbable.

It would also be desirable to provide a method and apparatus forinserting a suture anchor which results in a minimal number of insertionsteps and requires a minimal number of tools.

SUMMARY OF THE INVENTION

It is an object of this invention to provide a suture anchor which issimple and inexpensive to manufacture and easy to insert, as well as amethod of insertion which is relatively straightforward having a minimalnumber of steps, requiring a minimal number of insertion tools. Such asuture anchor reduces later complications such as bone weakening.

It is also an object of this invention to provide a suture anchor whichdoes not interfere with noninvasive examinations such as by radiographs,MRI, or CT, and is biocompatible, thus potentially causing bonestrengthening after implantation. Alternatively, the suture anchor maybe formed from a bioabsorbable material.

These and other objects of the invention are accomplished in accordancewith the principles of this invention by providing a substantially rigidsuture anchor, preferably made of bone, which is reoriented afterinsertion to be securely positioned inside a bone. A single insertiontool pushes the suture anchor through a previously drilled hole in thebone. The insertion tool includes at least a portion made of shapememory material which is deformed during insertion of the suture anchorbut which returns to its initial configuration when the suture anchor isfree to rotate (e.g., when in cancellous bone tissue), therebyreorienting the suture anchor to be securely positioned in the bone.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and advantages of the invention, its nature,and various features will be more apparent from the following detaileddescription of the preferred embodiments, taken in conjunction with theaccompanying drawings (in which like reference characters represent likeelements throughout), and in which:

FIG. 1 is a side view of a suture anchor in accordance with theprinciples of this invention;

FIG. 1A is a perspective view of the suture anchor shown in FIG. 1;

FIG. 2 is a side view of a modified suture anchor in accordance with theprinciples of this invention;

FIG. 2A is a perspective view of the modified suture anchor shown inFIG. 2;

FIG. 3 is a side view of an insertion tool in accordance with theprinciples of this invention;

FIG. 4 is a side view of an alternative embodiment of an insertion toolin accordance with the principles of this invention;

FIG. 5 is a side view of another alternative embodiment of an insertiontool in accordance with the principles of this invention;

FIG. 6 is a side view of a suture joined to the suture anchor of thepresent invention;

FIG. 7 is a side view of an alternative manner of joining a suture tothe suture anchor of the present invention; and

FIG. 8 is a side view of another alternative manner of joining a sutureto the suture anchor of the present invention.

FIG. 9 is a side view of a suture anchor mounted on an insertion tooland carrying a suture, in preparation for insertion into a bone;

FIG. 10 is a side view of a suture anchor mounted on an insertion tooland in the initial stages of insertion into a bone;

FIG. 11 is a side view of a suture anchor mounted on an insertion tool,shown once insertion into a bone has begun;

FIG. 12 is a view similar to that of FIG. 11, but shows further progressof the suture anchor and insertion tool into the bone, in the positionat which the insertion tool is in its most deformed state;

FIG. 13 is a view similar to that of FIG. 12, but shows the insertiontool beginning to resume its initial configuration;

FIG. 14 is a view similar to that of FIG. 13, but shows the sutureanchor almost completely inside the bone, but not yet within anchoringposition;

FIG. 15 is a side view of a suture anchor completely positioned incancellous bone tissue, the suture anchor still mounted on the insertiontool, which has resumed its initial configuration; and

FIG. 16 is a side view of a suture anchor in a final anchoring position,dismounted from the insertion tool.

DETAILED DESCRIPTION OF THE INVENTION

A suture anchor constructed in accordance with the principles of thepresent invention is shown in FIGS. 1 and 2. Suture anchors 20 and 22are formed from a material which is biocompatible. Preferably, theselected material strengthens the bone in which the anchor is inserted.Additionally, it is desirable for the selected material to betransparent to noninvasive examinations such as by radiograph (e.g.,X-ray). Accordingly, the most preferred material for the suture anchorsof the present invention is cortical bone. The suture anchor of thepresent invention is preferably formed from strips of cortical bone cutfrom the midshaft of a human femur. Autologous bone can be used, but canbe difficult to obtain. Allogeneic cortical bone is the preferredmaterial, however, the use of xenogeneic cortical bone tissue is alsocontemplated. The suture anchor of the present invention may also beformed of a suitable biocompatible polymer or biocompatible metal orother biocompatible material. Such metals and materials shouldpreferably be FDA approved for use in humans. Alternatively, one of avariety of known bioabsorbable materials may be used.

Although the method of insertion of the present invention may utilize asuture anchor of any desirable elongated shape, such as a cylinder, thesuture anchor of the present invention is preferably substantiallyconical, i.e., either a complete cone or a truncated cone (e.g., afrustum). As shown in FIG. 1, suture anchor 20 is completely conical,having an apex 24. A conical suture anchor may easily be formed byinserting an end of a strip of the desired material into a millingdevice. Such milling devices are well known in the art--and may bedesigned for milling bone or other materials in accordance with theprinciples of a common pencil sharpener. Apex 24, or a portion thereof,is useful for cutting through cancellous bone tissue once suture anchor20 passes through the cortical bone tissue. For greater strength in theapical area, it may be desirable to cut off the apex of the conicalsuture anchor to form a flattened trailing end 26, resulting in afrustoconical suture anchor 22, such as shown in FIG. 2. The amount bywhich the cone apex is truncated should preferably maximize thestructural strength of the apical region of the suture anchor, whileretaining a general conical shape. This enables travel throughcancellous bone tissue during reorientation of the suture anchor. Itshould be appreciated that the optimum shape of the suture anchor mayvary according to the site of use in the patient. One of ordinary skillin the art could determine, by routine experimentation, the optimumshape of the suture anchor for a particular application at a particularsite of use. As seen in FIGS. 1A and 2A, both suture anchor 20 andsuture anchor 22 preferably have generally circular conical surfaces(thereby facilitating manufacture) and each has a base 28 whichpreferably is cut oblique to the central axis of the cone. The angle atwhich base 28 is cut is discussed in more detail below.

Angle A of apex 24 is selected to efficiently cut through cancellousbone tissue and can range from 10°-60° . Preferably, apex angle A isbetween 20°-40°. The exact angle will depend on the milling apparatusused, and most typically is approximately 20°. Apex angle A generally isdetermined first, setting the range of possible lengths for the sutureanchor. The length of suture anchor 20 or 22 is selected to provide thestrongest suture anchor which can fit through the patient bone hole inwhich the suture anchor is to be positioned, and which can accommodatethe suture required for the particular operation. The size of thepatient bone hole through which the suture anchor is inserted is withinthe range of 1-12 mm, typically within 2-6 mm. Preferably, the patientbone hole is within 2.5-3.5 mm. The patient bone hole is formedaccording to any desired method, utilizing any suitable means.

Because base 28 of suture anchors 20 and 22 is cut oblique to thecentral axis, the angle formed between the conical surface and the baseof suture anchors 20 and 22 varies along the circumference of base 28.The leading bottom edge 30 (the first area of the edge of base 28 toenter the patient bone hole through which the suture anchor is to bepositioned) preferably has the smallest angle B between the conicalsurface and base 28. Trailing edge 32, opposite leading bottom edge 30,is at angle C, the largest angle between the conical surface and base28. The specific angle at which base 28 is cut with respect to thesuture anchor's central axis is determined primarily by the size of thepatient bone hole, to achieve the most easily insertable suture anchor.The measurement of apex angle A and the desired length of the sutureanchor also affect the angle at which base 28 should be cut. Typically,if the suture anchor is to be inserted with base 28 parallel to thewalls of the patient bone hole (as described in more detail below), base28 should be cut such that the distance from trailing edge 32, whenmeasured perpendicular to base 28, to the conical surface joiningleading edge 30 and apex 24 is no greater than the width of the patientbone hole. In other words, when the suture anchor is inserted into thepatient bone hole (with base 28 parallel to the walls of the patientbone hole) trailing edge 32 should be able to fit into the patient bonehole as well in order to ensure that the remainder of the suture anchorwill be able to fit through the patient bone hole. Preferably, thisdistance is approximately 0.2-0.5 mm less than the patient bone hole.Typically, the resulting angle C is between 90°-165°.

Both suture anchors 20 and 22 have an anchor bore 34 in which theinsertion tool is positioned to insert the suture anchor, and alsothrough which the suture generally is threaded. Accordingly, thediameter of bore 34 is determined by the diameters of the insertion toolto be used and the suture to be anchored, and typically is between1/32-1/16 inches. Bore 34 need not be cylindrical, and may have any of avariety of cross-sectional shapes. Preferably, the shape of bore 34includes a section in which the suture can travel to minimize contactbetween the suture and the insertion tool during the insertion process.Potential cross-sectional shapes for bore 34 thus include oblong,elliptical, tear-drop, a figure eight (thereby providing separate boresfor the suture and the insertion tool), substantially circular with aslot for the suture to run through, or any other shape that canaccommodate the suture as described. The entry and exit areas of bore 34preferably are chamfered to reduce stress on the suture when the sutureis pulled during suturing. Bore 34 is preferably cut at an angle obliqueto the axis of the suture anchor. Preferably, bore 34 and base 28, andflattened trailing end 26 (when present) are parallel. However, it iswithin the scope of the present invention to form bore 34, base 28, andflattened trailing end 26 at different angles with respect to the axisof the suture anchor.

In order to function properly, the insertion tool should be limited intravel through bore 34 of the suture anchor. Accordingly, the insertiontool of the present invention has a means for limiting the travel of itsinsertion end into bore 34. Examples of insertion tools having means forlimiting insertion end travel are shown in FIGS. 3-5.

Insertion tool 40 of FIG. 3 has a substantially straight elongated body42 ending with insertion end 44, which is inserted inside bore 34 of thesuture anchor. Bead 46 demarcates insertion end 44 from the remainder ofbody 42 and prevents body 42 from entering bore 34. The diameter ofinsertion end 44 should be sufficiently wide to provide a close fitinside bore 34 of the suture anchor (also accounting for the amount ofsuture material positioned inside bore 34). The diameter of bead 46should be substantially larger in diameter than bore 34 in order tolimit movement of insertion end 44 through bore 34.

Insertion tool 48 of FIG. 4 has a substantially straight elongated body50, similar to body 42. However, insertion end 52 is wedged, with thenarrowest part at the free end of insertion tool 48. The dimensions ofwedge 54 are selected to securely fit within bore 34 of the sutureanchor (with the suture also threaded through bore 34) to hold thesuture anchor during insertion into the patient bone. It will beappreciated that one or both sides of insertion tool 48 may be wedged.

Insertion tool 56 of FIG. 5 has a substantially straight elongated body58. Insertion end 60 is narrower than body 58 and distinctly begins atstep 62. Insertion end 60 must be sufficiently thick to form a tight fitwithin bore 34 of the suture anchor (with the suture also threadedthrough bore 34) during insertion into the patient bone hole. Again, itwill be appreciated that one or both sides of insertion tool 56 may bestepped.

For reasons as will be described in connection with the method ofinsertion, at least insertion ends 44, 52, and 60 of insertion tools 40,48, and 56, respectively, should be formed from a shape memory material.The memory should be retained such that the insertion end is notpermanently deformed during insertion of the suture anchor and willreturn the insertion end to an initial configuration (generally theconfiguration of the insertion end at the time it is initially mountedin bore 34, prior to insertion of the suture anchor into the patientbone). The preferred material for at least the insertion end of theinsertion tool is a nickel titanium alloy. Such materials are availablecommercially, under the names "NITINOL" or "TINEL" (RayChem) or"SENTINOL" (GAC International, Inc.). Such shape memory alloys are wellknown in the art. See, e.g., U.S. Pat. Nos. 4,505,767, and 4,565,589.However, any other shape retaining material sufficient for properlyinserting the suture anchor of the present invention into a patient bonehole may be used.

Any suitable means for attaching the suture to the suture anchor may beused within the scope of the invention. Suture 64 may be threadedthrough bore 34 of the suture anchor in any preferred manner, such asthose illustrated in FIGS. 6-8. In FIG. 6, one end of suture 64 isthreaded through bore 34 and looped around the conical surface of sutureanchor 20 adjacent leading edge 30. Thus, suture 64 passes throughsuture anchor 20 only once, as thread through the eye of a needle. Whenthreaded in this manner, suture 64 can freely travel through bore 34.Adjustment of the position of suture 64 through bore 34 by pulling oneof the free ends of suture 64 may cause the suture anchor to rotateapproximately 90°.

Suture 64 may, instead, be more fixedly threaded through bore 34, asshown in FIGS. 7 and 8. In FIG. 7, suture 64 is looped over sutureanchor 20, and the free ends of suture 64 are then threaded through theend of bore 34 adjacent leading edge 30, exiting bore 34 adjacenttrailing edge 32. Suture 64 is then pulled to tighten the loop aroundsuture anchor 20. When an end of suture 64 is pulled, suture anchor 20will barely rotate, if at all, maintaining bore 34 relatively parallelto the patient bone hole.

Suture 64 is knotted to anchor 20 in FIG. 8. As shown in FIG. 8, onlyone end of suture 64 is threaded through bore 34 as in FIG. 6. However,upon exiting bore 34, knot 66 is formed with the ends suture 64 at theexit of bore 34, preferably adjacent trailing edge 32. As in FIG. 7, themanner of threading shown in FIG. 8 may produce minimal rotation ofsuture anchor 20 if an end of suture 64 is pulled.

The preferred method of inserting the suture anchor of the presentinvention is illustrated in FIGS. 9-16. A patient bone hole 70 hasalready been drilled into patient bone 72. Patient bone hole 70 extendscompletely through cortical bone matter 74. Patient bone hole 70 mayalso extend, at least partially, through cancellous bone tissue 76,preferably to a depth about equal to the length of the suture anchor. Itwill be understood that any insertion tool with a shape memory insertionend may be used in the preferred insertion method. Moreover, anysuitable substantially rigid anchor with a bore for the insertion toolmay be used.

As shown in FIG. 9, suture anchor 20 is mounted on insertion end 44 ofinsertion tool 40, and suture 64 is threaded through bore 34. Insertionend 44 enters bore 34 adjacent trailing edge 32 of suture anchor 20 andexits (if at all) adjacent leading edge 30. Because insertion end 44 oftool 40 is securely positioned within bore 34, bore 34 is not easilydistinguishable, in the FIGS., from the outer surface of insertion end44. Bore 34 is preferably drilled parallel to base 28. Insertion tool 40is positioned parallel to the axis of patient bone hole 70, maintainingbore 34 and base 28 (if bore 34 is drilled parallel to base 28) parallelto patient bone hole 70, as well. Leading edge 30 of suture anchor 20 ispositioned to be the first portion of suture anchor 20 to enter patientbone hole 70.

Initial entry of suture anchor 20 into patient bone hole 70 is shown inFIG. 10. The conical surface extending between leading edge 30 and apex24 has not yet encountered patient bone hole 70. As alluded to above,this portion of the conical surface of suture anchor 20 should notencounter patient bone hole 70 until trailing edge 32 also encounterspatient bone hole 70.

Once the conical surface extending between leading edge 30 and apex 24encounters patient bone hole 70, suture anchor 20 begins to rotate orreorient, as shown in FIG. 11, in order to fit into patient bone hole70. Main body 42 of insertion tool 40 is maintained parallel to patientbone hole 70. Thus, when suture anchor 20 reorients, insertion end 44bends.

Typically, insertion end 44 is bent to the greatest extent immediatelybefore trailing edge 32 leaves the portion of patient bone hole 70 inpatient cortical bone tissue 74, as shown in FIG. 12. Once trailing edge32 begins travelling through patient cancellous bone tissue 76,insertion end 44 begins to resume its initially straight configuration,as shown in FIGS. 13 and 14. Preferably main body 42 of insertion tool40 is not as flexible as insertion end 44, and remains straightthroughout the insertion procedure. As best seen in FIG. 14, as sutureanchor 20 travels deeper into patient bone 72, right trailing edge 32travels further, and the greater influence the insertion tool's shapememory has over the configuration of insertion end 44.

Once apex 24 has cleared patient cortical bone tissue 74, and the entiresuture anchor is in cancellous bone tissue 76, insertion end 44 ofinsertion tool 40 is free to return to its original configuration, asshown in FIG. 15. The pointed apex 24 allows suture anchor 20 to travelcounterclockwise, easily cutting through cancellous bone tissue 76. Asshown in FIG. 16, insertion tool 40 can then be removed. Preferablysuture 64 is pulled up and away from patient bone 72 to firmly positionsuture anchor 20 in patient bone 72, preferably against the undersurfaceof cortical bone 74, within the transition region between cortical bonematter 74 and cancellous bone matter 76. Typically, suture 64 will besubstantially centered within patient bone hole 70, and suture anchor 20will be substantially horizontal. Suturing of body tissue to patientbone 72 can now be commenced.

It will be understood that the foregoing is merely illustrative of theprinciples of this invention, and that various modifications can be madeby those skilled in the art without departing from the scope and spiritof the invention. For example, the suture anchors and insertion toolsused in the preferred insertion method (illustrated in FIGS. 9-16) maybe formed in shapes other than those illustrated, but which willfunction in accordance with the method of the present invention.Moreover, it will be appreciated that although it is not necessary touse the insertion tools typically used during suture anchor insertion(such as cannulas), the use of such tools is contemplated within thescope of the present invention.

While we have hereinbefore described a number of embodiments of thisinvention, it is apparent that our basic embodiments can be altered toprovide other embodiments that utilize the inventive concepts of thisinvention. Therefore, it will be appreciated that the scope of thisinvention includes all alternative embodiments and variations which aredefined in the foregoing specification and by the claims appendedhereto; and the invention is not to be limited by the specificembodiments that have been presented herein by way of example.

What is claimed is:
 1. A suture anchor comprising:a substantially rigidconical body having a first end, a second end, and a conical surfacedisposed between said first and second ends wherein said second enddefines a base surface; a central axis extending from said first end andthrough said base surface; and a bore extending through saidsubstantially rigid conical body and across said conical surface.
 2. Thesuture anchor of claim 1 wherein said base surface is disposed at anoblique angle with respect to said central axis.
 3. The suture anchor ofclaim 1 wherein said bore is disposed in parallel relation to said basesurface.
 4. A suture anchor for inserting into live human bone so as tosecure a suture to said live human bone, said suture anchor comprising abone engaging portion adapted for fixedly engaging said live human boneand a suture attaching portion adapted for attaching a length of saidsuture to said anchor, said suture anchor consisting of a piece ofmilled bone, said bone engaging portion comprising a sharp edge formedon said piece of milled bone, and said suture attaching portioncomprising a hole formed in said piece of milled bone.
 5. The sutureanchor of claim 4, wherein said milled bone comprises human corticalbone.
 6. A system for anchoring a suture to live human bone through asubstantially cylindrical bone hole having a longitudinal axis, saidsystem comprising:an insertion tool having a flexible insertion endhaving shape memory for returning said insertion end to an initialconfiguration; and a substantially rigid suture anchor having a borethrough which said insertion end of said insertion tool is positioned;wherein said suture anchor is shaped and said bore is oriented such thatsaid insertion end of said insertion tool bends away from its initialconfiguration during insertion of said suture anchor through corticalbone tissue and springs back to its initial configuration when saidsuture anchor is positioned within cancellous bone tissue andaccordingly free to rotate.
 7. The system of claim 6 wherein said sutureanchor comprises:a conical body having a first end, a second end, and aconical surface disposed between said first and second ends wherein saidsecond end defines a base surface; and a central axis extending fromsaid first end and through said base surface.
 8. The system of claim 7wherein:said base surface is disposed at an oblique angle with respectto said central axis of said suture anchor; and said conical surface isa circular conical surface.
 9. The system of claim 8 wherein:said boreis parallel to said base surface; said suture anchor has a leading edgealong said base surface at which the angle between said base surface andsaid conical surface is most acute; said suture anchor has a trailingedge along said base surface at which the angle between said basesurface and said conical surface is greatest; said insertion end of saidinsertion tool enters said bore adjacent said trailing edge; and saidsuture anchor is sufficiently long to force said insertion end of saidinsertion tool to bend from its initial configuration when saidinsertion tool enters said bone hole parallel to said longitudinal axisof said bone hole and with said base surface of said suture anchorparallel to said longitudinal axis of said bone hole.
 10. The system ofclaim 7 wherein said conical body of said suture anchor isfrustoconical.
 11. The system of claim 6 wherein said insertion toolfurther includes means for limiting the movement of said insertion endinto said bore.
 12. A method of anchoring a suture to live human bonethrough a substantially cylindrical bone hole having a longitudinalaxis, said method comprising the steps of:selecting an insertion toolcomprising a main body and a flexible insertion end having shape memoryfor returning said insertion end to an initial configuration; selectinga substantially rigid suture anchor having a central axis and a bore atangle to said central axis; positioning said insertion end of saidinsertion tool through said bore; advancing said insertion tool towardssaid bone hole with said main body parallel to said longitudinal axisand said insertion end in its initial configuration, wherein said sutureanchor, as oriented on said insertion end, is too large to fit throughsaid bone hole; advancing said insertion tool and said suture anchorinto said bone hole, causing said suture anchor to reorient by bendingsaid insertion end of said insertion tool; and advancing said insertiontool into said bone hole until said shape memory insertion end is freeto return to its initial configuration, thereby reorienting said sutureanchor to its orientation prior to insertion into said bone hole. 13.The method of claim 12 further including the step of inserting saidsuture through said bore in which said insertion end is inserted. 14.The method of claim 13 further including the step of pulling said sutureaway from said bone hole after said suture anchor has been reorientedinside said bone hole, to thereby further secure said suture anchor insaid bone hole.
 15. An insertion tool for inserting a suture anchorthrough a substantially cylindrical hole in a live human bone andcausing said suture anchor to be anchored in said live human bone, saidsuture anchor being substantially rigid and having a bore through whichan end of said insertion tool is positioned, said suture anchor beingshaped and said bore being oriented such that when said insertion toolis positioned in said bore and maintained parallel to said hole duringinsertion of said suture anchor said suture anchor must be reoriented inorder to fit into said hole, said insertion tool comprising:an elongatedmain body having a first end and a second end; and an insertion endcoupled to said first end of said main body for inserting into said boreof said suture anchor, said insertion end having shape memory; wherein:said insertion end has an initial configuration before insertion of saidsuture anchor through said hole; upon insertion of said suture anchorthrough said hole, said suture anchor causes said insertion end to bendfrom said initial configuration so that said suture anchor can fitthrough said hole while said main body of said insertion tool travelsparallel to said hole; and said insertion end returns to said initialconfiguration when said suture anchor is positioned in cancellous bonetissue, thereby reorienting said suture anchor to be firmly anchored insaid live human bone.
 16. The insertion tool of claim 15 furtherincluding means for limiting the movement of said insertion end intosaid bore.
 17. The insertion tool of claim 16 wherein said means forlimiting movement comprises a thickened area between said main body andsaid insertion end.
 18. A suture anchor comprising:a conical body havinga first end, a second end, and a substantially continuous conicalsurface disposed therebetween, and further wherein said second end ofsaid conical body defines a base surface; an axis passing through acentral portion of said first end and through said base surface; and abore passing through said conical body in proximate, non-intersectingrelation to said base surface.
 19. The suture anchor of claim 18 whereinsaid base surface is disposed at an oblique angle with respect to saidaxis.
 20. The suture anchor of claim 18 wherein said bore is disposed inparallel relation to said base surface.
 21. The suture anchor of claim18 consisting of milled bone.
 22. The suture anchor of claim 21 whereinsaid milled bone comprises human cortical bone.
 23. The suture anchor ofclaim 18 comprising a bioabsorbable material.
 24. The suture anchor ofclaim 18 comprising a biocompatible polymer.
 25. The suture anchor ofclaim 18 comprising a biocompatible metal.
 26. A suture anchorcomprising:a substantially rigid conical body having a first end, asecond end, and a conical surface disposed between said first and secondends, wherein said second end defines a base surface; and a central axisextending from said first end and through said base surface; said bodyhaving therein a bore extending through said body with the ends of saidbore disposed in said conical surface.
 27. The suture anchor of claim 26wherein said base surface is substantially planar and is disposed at anoblique angle to said central axis.
 28. The suture anchor of claim 27wherein said bore extends substantially parallel to said base surface.29. The suture anchor of claim 26 wherein said base surface issubstantially planar and is elliptical in configuration.